Two-way impeller in a centrifugal pump having vertical drive shaft

ABSTRACT

In a two-way impeller in a centrifugal pump having a vertical drive shaft the impeller channels are formed such that a circulation flow is provided outwardly in the lower part thereof and inwardly in the upper part. By openings in the impeller between the two impeller inlets a suction effect is induced in a direction toward the upper inlet of the impeller. On the pump drive shaft and below the two-way impeller a centripetal-inducer may be mounted.

United States Patent 11 1 Navelsaker 1 1 Sept. 9, 1975 TWO-WAY IMPELLERIN A CENTRIFUGAL PUMP HAVING VERTICAL DRIVE SHAFT [75] Inventor: OlavRasmusson Navelsaker,

Nordengveien, Norway [73] Assignee: Thune-Eureka A/S, Oslo, Norway [22]Filed: Feb. 5, 1974 [21] Appl. No.: 439,766

[30} Foreign Application Priority Data July 5, 1973 Norway 2767/73 [52]US. Cl. 415/53; 415/98; 415/143; 417/424 [51] Int. Cl. F04D 7/02; F04D29/26 [58] Field of Search 415/98, 120, 143, 53; 417/199 A, 424

[56] References Cited UNITED STATES PATENTS 2,383,424 8/1945 Stepanoff415/98 2,463,251 3/1949 Curtis 2,465,625 3/1949 Aue 2,471,174 5/1949Trumpler..... 2,581,828 l/l952 Adams 417/199 A 2,985,108 5 1961 Stoneret al. 415/120 3,250,440 5/1966 Trout 415/143 3,721,504 3 1973Crisafulli 417/424 FOREIGN PATENTS OR APPLICATIONS 152,673 1922 UnitedKingdom 415/53 646,436 6/1937 Germany 368,879 3 1939 Italy 415/531,279,260 11/1961 France 415/98 970,265 9/1958 Germany 415/98 932,3867/1963 United Kingdom... 415/143 2,889 1895 United Kingdom 415/98Primary Examiner-Henry F. Raduazo Attorney, Agent, or Firm-Young &Thompson [57] ABSTRACT In a two-way impeller in a centrifugal pumphaving a vertical drive shaft the impeller channels are formed such thata circulation flow is provided outwardly in the lower part thereof andinwardly in the upper part. By openings in the impeller between the twoimpeller inlets a suction effect is induced in a direction toward theupper inlet of the impeller. On the pump drive shaft and below thetwo-way impeller a centripetalinducer may be mounted.

2 Claims, 1 Drawing Figure TWO-WAY IMPELLER IN A CENTRIFUGAL PUMP HAVINGVERTICAL DRIVE SHAFT The invention relates to a two-way impeller in acentrifugal pump having a vertical drive shaft, and the invention isdeveloped in particular with relation to socalled submergiblecentrifugal pumps, utilized for the pumping of cargo in the tanks ofships.

As the level of the cargo in the tank of a ship sinks, problems of airintermixture arise which substantially reduce the efficiency of thepump. It is possible to im prove this condition to a great degree byarranging the suction opening of the pump upwardly; however, theadvantage of a pump having the suction opening thereof facing downwardlyis then lost, this advantage being the possibility of positioning thesuction opening as close to the bottom of the tank as possible. If a twoway impeller is used, i.e., an impeller having suction openings both atthe top and at the bottom and having a common blade channel outlet forthe two suction inlets, it is possible to a certain degree to combinethe advantages of the two arrangements of pump impeller. The inventionrelates to such a two-way impeller and the object is to provide aconstruction such that the lower part of the impeller also can bevented. ln accor dance with the invention, this is achieved in that theimpeller channels are formed so as to provide a circulation flowoutwardly in the lower part and inwardly in the upper part of theoutlet, on zero distribution in the upper half part.

Advantageously, openings may be provided in the impeller between the twooutlets formed so as to create a suction effect in a direction towardthe upper impeller inlet in order to provide venting.

In the meridian section, the lower part of the impeller channel may havea relatively larger inlet cross-section than the upper part in order toachieve the intended improvement in suction effect. To achieve thecirculation flow, the edge of the blade outlet in the meridian sectionfollows a bent line, and the bent edge of the blade outlet extends, forexample, vertically at its lower part, and in the upper part of theimpeller channel, inclines inwardly toward the longitudinal axis of thepump.

Advantageously, a centripetal-inducer is mounted below the two-wayimpeller on the same drive shaft, this centripetal-inducer deliveringliquid to the downwardly facing inlet when the liquid level approacheszero.

The invention is further described hereinbelow with reference to thedrawing which illustrates a section through a two-way impeller inaccordance with the invention.

In the drawing, the drive shaft is signified by l. A two-way impeller 2is mounted on the drive shaft in a manner known per se, and acentripetal-inducer 3 is mounted at the end of the drive shaft.

The two-way impeller is provided with an upper suction inlet 4 and alower suction inlet 5 with blade channels 6 common to the two suctioninlets. The bearing housing of the drive shaft 1 is signified by 7 andthe pump housing is indicated at 8. The flow directions are indicated byarrows at the suction side and outlet of the two-way impeller, and theflow direction in the centripetal-inducer also is indicated by an arrow.

In the blade channel 6 indicated, the curved arrow indicates acirculation flow which can be produced by several known methods. In theembodiment example, the circulation flow is induced in that the lowerpart of the blade channel is of greater diameter than the upper part. Inthe meridian section illustrated, the edge of the blade outlet follows abent line and extends vertically at 9 in the lower part and inclinesinwardly at 10 toward the longitudinal axis of the pump in the upperpart of the blade channel. Upon so-called zero distribution, thisembodiment will induce the circulation flow indicated. This effectsventing in the lower channels also.

In order further to increase the venting effect, openings 11 may beprovided, as illustrated, formed such that an overpressure is formed onthe underside thereof, a suction effect indicated by the symbols andbeing produced on the upper side.

Having described my invention, I claim:

1. A vertical centrifugal pump comprising a casing, an impeller, meansmounting said impeller for rotation in said casing about a verticalaxis, said impeller comprising upper and lower annular end members thatare vertically spaced apart and spaced radially outwardly from the axisof rotation of said impeller, a partition member disposed between andspaced from said end members, blades interconnecting each of said endmembers with said partition member to define channels between said endmembers and said blades and said partition member that open radiallyoutwardly and upwardly and downwardly, said casing having passagescommunicating radially outwardly with said channels between said endmembers and upwardly with said channels between said upper end memberand said partition member, said partition member having upwardlyextending openings therethrough to vent the lower of said channels tothe upper of said channels, the upper of said end members being of lessdiameter than the lower of said end members to provide a flow path ofrecirculation.

2. A centrifugal pump as claimed in claim 1, and a centripetal inducermounted on and below said impeller.

1. A vertical centrifugal pump comprising a casing, an impeller, means mounting said impeller for rotation in said casing about a vertical axis, said impeller comprising upper and lower annular end members that are vertically spaced apart and spaced radially outwardly from the axis of rotation of said impeller, a partition member disposed between and spaced from said end members, blades interconnecting each of said end members with said partition member to define channels between said end members and said blades and said partition member that open radially outwardly and upwardly and downwardly, said casing having passages communicating radially outwardly with said channels between said end members and upwardly with said channels between said upper end member and said partition member, said partition member having upwardly extending openings therethrough to vent the lower of said channels to the upper of said channels, the upper of said end members being of less diameter than the lower of said end members to provide a flow path of recirculation.
 2. A centrifugal pump as claimed in claim 1, and a centripetal inducer mounted on and below said impeller. 